Glucose is known as one of the most important energy sources for maintaining the survival of cells, from mammals to Escherichia coli and yeast, and in particular, the brain uses glucose as the sole energy source. Glucose has enantiomers D-glucose and L-glucose, and among these enantiomers, only D-glucose can be utilized as an energy source by organisms, and living cells have a mechanism of selectively incorporating D-glucose mediated by a transport protein in the cell membrane such as a glucose transporter and utilizing it.
In the past, a research as to how organisms incorporate D-glucose into cells and utilize it has been performed by determining the amount of a radioisotope in cells using, for example, radiolabelled D-glucose or a derivative thereof (such as radiolabelled D-deoxyglucose). However, although this method is excellent in quantitative determination, it has a problem that the sensitivity is low, and also has a disadvantage from a measurement method point of view that it cannot continuously observe the manner that living cells incorporate D-glucose in real time. Therefore, this method cannot be used in a study of the process of dynamic incorporation of D-glucose into living cells.
In view of the above circumstances, the group of the present inventors proposed a method using 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-D-glucose (2-NBDG) that is represented by the following structural formula and emits green fluorescence and is obtained by attaching an N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino group as a fluorescent chromophore to the 2-position of D-deoxyglucose as the method which can be used in a study of the process of dynamic incorporation of D-glucose into living cells, and the usefulness of the method was demonstrated using various mammalian cells (Non-patent document 1).

This method utilizes the property of 2-NBDG that it is selectively incorporated into living cells, and by tracking changes in the fluorescence intensity due to the incorporation, the dynamic activity of cells for the incorporation of D-glucose can be quantitatively determined. Therefore, this method has been evaluated by researchers around the world as an innovative method in studies as to how organisms incorporate D-glucose into cells and utilize it, and now is positioned as a standard protocol essential in this research field (Non-patent document 2).